A quantitative mechanistic model has been formulated to account for the kinetics of appearance of small soluble oligomers of fibrin and/or fibrinogen following the addition of thrombin to fibrinogen solutions, as previously measured in this laboratory. An automated microfractionating device has been developed which enables the concentration gradients of radiolabeled macromolecules subjected to ultracentrifugation to be quantiated with high precision and sensitivity. The theory of sedimentation equilibrium has been extended to solutions which contain high concentrations of macromolecules and are far from thermodynamically ideal. The theory of the effect of excluded volume on the self-association of macromolecules has been generalized two-dimensional systems and applied to simplified models of membrane proteins. A novel method of acquiring digital or analog data from individual laboratory instruments has been developed, which involves temporary storage in a small battery-backed memory module prior to transfer to a central laboratory data processing/storage facility.